The objective of this research is to determine the effect of perinatal (in utero or via lactation) exposure to foreign compounds on the development of basal and inducible mixed function oxidase (MFO) activities later in life. Perinatal exposure will be provided by classical enzyme inducers such as phenobarbital and Beta-naphthoflavone administered to rat dams. Subsequent MFO activities of the Fl offspring will be monitored from birth through adulthood. The relevance of these treatments on the intact animal will be studied by determining the disposition of two carcinogens, aflatoxin B1 and 3-methylcholanthrene. The quantities of ultimate carcinogen produced in vivo and covalently reacting with tissue macromolecules will be used to measure altered carcinogen metabolism. This research is designed to determine whether perinatal exposure to xenobiotics presets the basal level or inducibility of MFO enzyme activity and, perhaps alters the individuals susceptibility to chemically-induced cancers.